Hi, I'm new here ... was wondering if I can get help figuring out which Manga this is.

• Protagonist is a Female Assassin/Mercenary. She uses a gun (i think)
• One of here enenies is a Middle-aged Male that uses a Nail Gun as a weapon
• Her boss or teammate has a Bullet-Proof Afro/Wig
• Protagonis and Nail Gunner teamed up to raid a building
• I think they found a child in the building and he was hand-cuffed to a case with medicine in it.

That's all that I can remember, sorry if it's insufficient.